The invention relates in general to a method and apparatus for securing a grip element to a crockery or pottery article and, more particularly, to a method and apparatus in which an adhesive is used to join a grip element to such articles.
Grip elements such as grips, knobs, handles, etc., are often formed of plastic. These grip elements are mechanically secured to a crockery or pottery article by metal parts such as clamping bands, disks or washers and screws. When the crockery or pottery article, usually pots, pans, lids, jugs, jars, etc., made from glass, glass ceramic, ceramic, porcelain, glazed earthenware or the like, is intended to be used in a microwave oven, no metal parts can be used to attach the grip element to the article. In such cases, an adhesive can be used. The adhesive used for this purpose must meet the stringent demands of cooking operations. The adhesive must form a firm bond both with the grip element and the crockery or pottery article. It must be elastic enough to compensate for the great differences in the coefficients of expansion. For example, glass has a coefficient of expansion of 3.3.times.10.sup.-6 /K, whereas the coefficient of expansion of plastic is about 80.times.10.sup.-6 /K. In addition, the adhesive must be temperature-resistant up to about 280.degree. C., it must have an adequate shear resistance and be resistant to acids, alkalis and foodstuffs. Adhesives satisfying these criteria are often highly viscous and difficult to use.
The use of adhesives to secure a plastic grip to a jug of glass or ceramic is known from DE-PS 3,048,783 and 3,109,759. The plastic/glass adhesive bond is generally unsuitable for cooking because the adhesive is temperature-resistant only up to about 100.degree. C. These patents disclose the amount of adhesive which can be used to secure the plastic grip to the jug. The adhesive flows through holes in the grip and can form thickened portions on a side of the grip remote from the side joined to the jug. These thickened or enlarged portions of adhesive form a lock and mechanically hold the grip to the glass jug. Adhesives for such joints cannot, however, be of lower viscosity because otherwise the thickened adhesive portion and resultant mechanical lock will not be formed.
It is therefore desirable to provide a method and apparatus for adhesively securing a grip element to a piece of crockery or pottery which fulfills the aforementioned conditions and avoids the disadvantages of the prior art.